External H/d Problems

[i built it]

I built my pc, My spec is A P4 3.2GHZ, 1GB memory, 128MB (FX5500 AGP 8X), CD-RW & DVD-RW and a External 80GB hard drive.

My Problem is my External hard drive, its on a USB port, i have changed ports still no joy, it never use to do that until recently, when i play my music from the EXTERNAL HARD DRIVE the CPU shoots up tp 100% and hovers around 85% - 100% and slows the pc down.
I have done endless virus scans & defrag it still happens!!!

Has anyone got any cures or remedies for this problem ???

[mondsi]

Try to investigate the "Windows task manager" by pressing ctrl+Alt+del, then click the "Processes" tab, on this tab try to investigate the cpu column and look for the .exe that use a lot of cpu usage. after you've done this investigation. tell me what process is it.